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FLORA INDICA.                                  235
in all its bearings: he considers—1. That the two cotyledons may be regarded as
one split cotyledon; against which we would urge, that the plumule ascends directly
from between them, that the first pair of leaves are at right angles to them, and
that the relation of the plumule to these lobes differs in no way from what is seen in
other Dicotyledons, and is not like that of any Monocotyledon known to us. 2. He
suggests a comparison of the embryo with those of Apsnogeton, Cymodocea, and Po-
sidonia. This we have made; they are exalbuminons seeds, with strictly monocoty-
ledonous coleorhizal embryos, not contained in the sac of the amnios. Of these,
Aponogeton, the germination of which we have studied (see also Edgeworth in Hook.
Journ. Bot. 184*4, p. 405. t. xvii. and xviii.), has a linear plumnle parallel to the
cotyledon, and lying in a narrow slit or fold of the latter. In Posidonia also the
cotyledon is longitudinally cleft on one side, and the plumule, which is lodged in the
slit, is inflexed. In Cymodocea the plumule is enclosed in the acute cotyledon.
3. Another supposed anomaly is founded on the cotyledons not being contracted at
their bases, and the plumule having an oblique position relatively to them; the latter
observation, however, is not confirmed, and very many dicotyledonous embryos are
continuous with the radicle in diameter, or even taper upward from it.
2. Germination. This we have studied in three species of Nympkcea, in Euryale
and Victoria, all of which present the same appearance, with little modification.
The radicle and bases of the cotyledons protrude through an orifice at the micropylar
end of the seed, caused (as explained by Trecul) by-the falling away of a little oper-
culum opposite the radicle. The radicle turns downwards, and becomes a filiform
rootlet, or is sometimes altogether arrested. The body of the cotyledons remains
within the seed, and the plumule ascends from between their cxserted bases, attains
a considerable length, and gives off two strictly opposite leaves at right angles to the
cotyledons; of these leaves one has a vaginate petiole, with adventitious rootlets de-
veloped at its base, and a lanceolate lamina with reticulate venation'; the other is
reduced to a mere filiforhi subulate petiole, and has no rootlets. Within these first
pair of leaves two others ate developed at right angles to them, thj sheathing base
of the petiole of the lower embracing that of the upper,.which is much the smallest;
the first pair of leaves we hence consider to be opposite,, ajad the following alternate.
Trecul, on the other hand, by calling the leaf reduced to a petiole the first, and the
larger one the second, would seem to imply that the' fiyafr two leaves are alternate, or
developed at different epochs; but they are so strictly opposite (at the apex of the
terete tigellus) in the numerous specimens we have examined, and in all three genera,
that we are inclined to consider their dissimilarity in size to be due -to unequal
development. In Nuphar lutea, however (which we have not examined), Trecul
describes-the first leaf as springing at once from between the cotyledons, and the
second from the axil of the first.
Near the cotyledouary end of the radicle of Nympfusa is a swollen ring, which,
liudley suggests may be analogous to a coleorhiza; hut this never forms a sheath to
the radicle, is not developed till the radicle germinates, and, as Trecul has shown, it
performs the office of adventitious rootlets, and hence its function commences when
jhnt of a colcorhiza ceases. In EuryaU and Victoria it sends forth horizontal pro-
cesses, in all respects like rootlets, which perform the office of the radicle, which
most frequently in these genera does not elongate. The radicle itself invariably
decays soon after the leaves are formed, with the tigellus and remains of the seed,
and the plant is nourished by the adventitious rootlets at the bases of the petioles.
These rootlets emerge enclosed in a cellular sheath, which elongates considerably, and
at last tears away, leaving a tubular sheath at the base, and calyptra at the apex of
the rootlet. The formation of this and of the vascular bundles in the rhizome, root-
lei, cotyledons, etc., are beautifully demonstrated in TrecaTs papers, to which -we
refer for their minute anatomy. Trecul considers that the cotyledons being retained
within the seed, and the radicle not becoming the root of the future plant, are both
indications of an, approach to Monocotyledons. This is a point which we are not pre-
pared to discuss, "We cannot, however, withhold an impression that neither of these
phenomena are confined to Monocotyledons; but the point has'not, so far as we are